For more than two weeks now, Chandigarh has witnessed a steady decline in new positive cases, with the number of active cases also seeing a decrease. From 810 active cases on October 20 to 744 cases on October 21, the UT witnessed a sharp decrease on October 22 with 712 active cases. On October 23, 697 active cases were reported and the number fell to 674 on October 24 and 653 on October 25.
According to the latest data, the active ratio of the UT is 4.8 per cent, which means for every 100 confirmed cases, five are currently infected. The average growth rate is 0.8 per cent. In the last one week, the number of new infections has grown by an average of 0.4 per cent every day. The recovery ratio in Chandigarh is 93.6 per cent; for every 100 confirmed cases, 94 have recovered from the virus. The last week has seen the number of new COVID positive cases less than 100, with 61 cases reported on October 25, 57 cases reported on October 24, 72 on October 23, 53 on October 22, 54 on October 21, 57 on October 20.
The recent trend of falling COVID cases, says Dr Vikas Bhutani, director, Internal Medicine, Fortis Hospital, could be attributed to development of anti-COVID antibodies in the community due to increased number of sub-clinical infections and undocumented mild infections in the community apart from those reported. Also, the sensitivity of RT PCR test for SARS 2-CoV is around 67-70 per cent, meaning thereby, out of 100 positive infections, 30-33 cases are missed, but all of them would develop antibodies leading to an increase in sero-positivity rates. “Maybe we are nearing some sort of herd immunity in pockets where a large chunk of population has been affected but we don’t have sufficient evidence to say so at present.”
Meanwhile, epidemiologists across the globe have started debating that herd-immunity threshold has been reached in regions that have already suffered major outbreaks. Herd immunity is the level of immunity in the population needed before a viral illness dies out and it varies from disease to disease, and it may happen due to infection itself or vaccination. The scientific journal Nature estimates that the herd immunity threshold for COVID-19 may be at 50 per cent of the population. “As per the latest data, we may be towards the tail end of the first peak in the Tricity, but the models do suggest that a second wave of COVID-19 is expected to arrive with the onset of winter season and which may achieve a peak by December 20 to January 21. So, the word of advice is that even though the number of active cases is declining, precautions such as social distancing, personal hygiene, frequent hand washing and face masks should continue at the same level so as to overcome the second wave also, in case we do see it.”
Testing has been stepped up during week days, with 1,064 samples tested on October 23, 1,140 samples tested on October 22, 1,284 on October 11, 1,134 on October 21 and 931 on October 20. Testing not only the sick, but also reaching out to the larger community, says a leading health economist is the only way to control spread of infection, as more testing will lead to tracing asymptomatic patients, contact tracing, isolation of positive cases and also motivate people to get tested.
Dr A K Aggarwal, Professor, Department of Community Medicine and School of Public Health, PGIMER, looks at these numbers, including the high positivity ratio of Chandigarh, differently and with skepticism. “The interpretation of these numbers is not so simple, for there are many factors that have to be kept in mind. If you are increasing testing in populations and areas that are healthy and less exposed and don’t extend to patients where positivity chances are high, then of course, the number of positive cases will be less. As for if we are seeing the end of the first wave, we don’t know at this stage of time,” Dr Aggarwal explains.
Increasing testing in larger communities, urban slums, clusters where chances of positivity are high is paramount, he believes, so that there is also contact tracing and isolation. “Antibody testing in larger populations will give us a clear picture of where we stand and will help us target areas where chances of infection are more and so immediate contact tracing can be done. In this change of weather and drop in temperature, cases of flu are on the rise, and it is difficult to distinguish between the two. So we need to be more cautious and careful,” the doctor adds.
Prof R K Kochhar, head, Department of Gastroenterology and Sub-Dean PGIMER, says that the declining number of cases in Chandigarh does point towards the fact that the initial surge is coming down, as we can witness the same trend in Punjab and Haryana as well. As for the second wave, Dr Kochhar says it is expected, like we are witnessing across the USA and Europe. “Even in the case of Spanish Flu, there were more than two waves. Also, we have to keep in mind that not even 10 per cent of the population is infected so far, so 90 per cent of the people are not exposed to the virus. As for the high positivity rate, we all know that Chandigarh has lagged behind in testing.”
The Rt, or reproduction number indicates how one infected person transmits the disease to another and a high Rt shows that the disease is spreading fast in a population. “When Rt is below one, it means the transmission will stop. But personally, I feel this is the time to take more caution, as the festive season and winters are approaching and there will be more crowding outdoors, and along with it, there will be an increase in flu cases. Taking precautions and following guidelines is the only way to protect ourselves and others,” Dr Kochhar adds.
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